There's an unspoken assumption in jazz that, when one hears someone's solo, at some level of consciousness one is bearing in mind that the soloist is improvising, and that the soloist should get some love for that fact in and of itself---the outcome of said "improvisation" being of secondary value at most and irrelevant at least. It's almost as if the listener is supposed to be impressed by the fact that the soloist is "improvising" (more on that later). Using this line of reasoning one could extrapolate that the improviser should get extra consideration because he/she is not playing something notated by a composer. The internal dialog of the listener might be along the lines of: "Wow! I can't believe that they're improvising that!". Truthfully---whether or not something is improvised or not shouldn't even be part of the equation. The criteria should only be: "How does it sound to me? Do I like it? Is something being expressed or conveyed by the solo---or is it just pyrotechnics?". Sometimes the notion that improvisation is taking place is a form of apologetics in which the listener might be unconsciously adding the word "but" to the equation: "Okay... granted, the content might not be all that great---BUT they're improvising!". Nonsense. You don't get extra points because you're "improvising". On to the next point, one that hopefully will shed a bit of light on my use of quotation marks in conjunction with the word "improvisation" (oops... I did it again). In a musical context, improvisation is a funny word; one that brings up all kinds of arcane questions about personal agency and cause-and-effect. Here's what I know for sure: The tail frequently wags the dog and even the best "improvisers" are sometimes led to their musical decisions by motor response (what falls under the fingers) and habituated response. I've always been a huge fan of Keith Jarrett and have held him in the highest regard as an improviser. Still, if you've heard enough of his solos, you hear the repetition of lines (in different solos and recordings) with some frequency. Same with ALL of the great ones; Herbie, Chick, Kenny Garrett, et al. It could be argued that these people (and all jazz musicians) develop a vocabulary and that they draw on that vocabulary as needed. That's the conventional wisdom anyway. Conversely, it could be argued that the artist in question is going to play that same line (or a close variation thereof) every time they see the symbol G-#7, because that's just what comes to mind for them as a conditioned response to that environment. A friend of mine was performing at a jazz festival in which he was doing a tribute to Oscar Peterson, for which that friend decided to play transcriptions of Oscar's improvised solos. I thought it was a groovy idea, one that would inevitably lead people to check out Oscar. (As an aside, Oscar used a ton of familiar lines in his improvisation). Anyway, after my friend's performance, a famous New York jazz pianist who was appearing at the festival---chastised my friend, telling him in essence that he should be playing his own improvised solos. My friend went on to explain that he was treating it like Classical music and as an historical artifact; In my opinion, a completely worthy endeavor. Anyway, the upshot was that the famous New York jazz pianist performed his set, and those that had been privy to the earlier conversation were amused to hear famous-New-York-guy play the same line in just about every one of his solos. Vocabulary? Maybe. Conditioned, habituated responses? Maybe. People tend to neglect just how quickly the language metaphor breaks down when applied to music. In the strictest sense, musical language and vocabulary are just not the same----not at all. I heard Seattle pianist Randy Halberstadt speak of "modular" playing, where one just modularly plugs in a memorized lick (line or fragment of a line) over the appropriate harmonic environment (chord). There's nothing at all wrong with that approach. Everyone just does the best that they can do. One could also argue that often times in composed music a composer may revisit lines time and again. I know that's true as well. I see even the Almighty J.S. Bach reuse thematic material in different pieces. Still, in those instances I'm not getting the impression that Bach was saddled with limitations of imagination. It's just part of the big question: Can one truly improvise?---particularly within the confines of tonal music? Beats me.